JP-2011-152017A discloses a bridgeless power factor correction (PFC) circuit including two series circuits, each of which has a diode and a semiconductor switching device (an N-channel MOSFET). A connection point between the diode and the switching device of one series circuit is connected to a connection point between the diode and the switching device of the other series circuit through an inductor and an AC power source. This configuration reduces loss in conversion from an AC voltage to a DC voltage.
In the above circuit, the switching device switches between an ON state and an OFF state at a high speed. Therefore, when the switching device switches from one of the ON state and the OFF state to the other of the ON state and the OFF state, a surge voltage occurs. Specifically, when the switching device switches from the ON state to the OFF state, a surge voltage occurs, and when the switching device switches from the OFF state to the ON state, a surge voltage due to a recovery of the diode occurs. As a result, loss in an AC-DC converter may be increased, reliability of the switching device and the diode may be is degraded, and high-frequency noise may be produced.